Scottish people call a sausage sandwich "sausage bap" or even "roll and sausage".
You might also hear Scottish people refer to a sausage sandwich as a "piece and sausage", especially when it's a sliced loaf instead of a roll.
The term "bap" is a soft and often round bread roll which is also used traditionally for a sausage sandwich.
Sausage Bap is a very common term for sausage sandwiches that are made with soft, bread rolls that are known as a "bap".
And roll and sausage is a term that emphasizes that the sausage is served in a roll and is also widely used in Scotland.
When the sausage sandwich is called piece and sausage, the "piece" can refer to any snack or sandwich in Scotland, so "piece and sausage" is a straightforward way of asking for a sausage in sliced bread.
And in some parts of Scotland, especially the North East, a "softie" is also the local name for a sausage sandwich, with options that include a "square sausage softie".